1. Field of the Invention
The present invention relates to a data processing apparatus including a compact-disk read only memory (called CD-ROM) and method thereof.
In recent years personal computers have become more and more high-speed and powerful. With the increase in data quantity and diversification of data processing, demand for an external storage medium with a large storage capacity is ever increasing. A personal computer equipped with a CD-ROM, (which is a non-magnetic disk) has a much larger storage capacity than a personal computer equipped with magnetic disks.
Although audio data, video data and data for information processing (hereinafter called computer data) can be recorded on a CD-ROM per se, conventional CD-ROMs record these types of data in track units, so that these types of data cannot be read at the same time for use in practically concurrent processing (hereinafter a CD-ROM of this data format is called a CD-ROM format disk). However, demand for a data processing system which can read these types of data simultaneously from a single CD-ROM and can perform data processing, audio-reproducing and graphics-displaying in synchronization, is ever increasing. To meet this demand, a CD-ROM XA (Extended Architecture) system, which is the extention of a the basic capabilities of CD-ROM system, is being established as an international standard.
The CD-ROM XA system allows high-quality voices, such as those recorded on audio compact disks to be reproduced in synchronization with graphics being displayed, by recording both audio and video data in continuous sectors of a disk track. It also allows audio, video and computer data to be processed independently with individual processors, therefore reducing the load of a central processing unit (CPU) which processes computer data, by recording such data together in a single track in sector units (hereinafter a CD-ROM of this data format is called a CD-ROM XA format disk). The CD-ROM XA system records audio data in a compressed data format to allow room for other information (i.e., video and computer data).
Accordingly, a data processing apparatus including a CD-ROM drive which can control both tile CD-ROM format disk and CD-ROM XA format disk economically and effectively, is in great demand.
2. Description of the Related Art
Conventionally, two types of CD ROM readers are used to control a CD-ROM drive to read data from a CD-ROM and to provide the data read to a processor. The first type is an individual circuit (including firmware) specifically designed either for a CD-ROM format or CD-ROM XA format disk and the second type has the above two circuits combined, designed for the CD-ROM format disk and the CD-ROM XA format disk.
Accordingly, a problem is that, in order to control both CD-ROM format and CD-ROM XA format disks, the first-type CD-ROM reader is inconvenient because two circuits must be changed, these two circuits being the ones for controlling the CD-ROM format disk and the CD-ROM XA format disk, respectively.
Another problem is that the second type CD-ROM reader is costly because two circuits of the first-type are required to control both CD-ROM format and CD-ROM XA format disks.
Still another problem is that the second-type CD-ROM reader is large-sized and inferior in reliability because of the large amount of circuitry required to control both the CD-ROM format and CD-ROM XA format disks.